Smart cards, which are about the size of a credit card or smaller and that have contact pads on their lower surfaces, contain memory chips that are read out or written into by smart card connectors. A common type of smart card connector has a card-receiving slot open at its rear end, into which a card can be forwardly inserted, until the card is fully inserted and blade contacts engage the card pads. The connector is mounted on a circuit board, with the contacts having tails soldered to traces on the board. Most contacts are signal contacts that carry signals, and usually one contact is a ground contact.
The contact pads are usually arranged in two rows, including forward and rearward rows, and the blade contacts are usually arranged in two rows including forward and rearward rows. The blade contacts of the forward row extend to the front end of the connector where their tails are soldered to circuit board traces, and the blade contacts of the rear row extend to the rear end of the connector where their tails are soldered to circuit board traces. It is highly desirable that a region above the tails be open during and immediately after soldering, to enable inspection of the solder joints.
Smart card connectors that are used in public places, and especially when unattended, are subject to fraud attempts. One type of fraud attempt involves inserting a conductor from a position at the rear of the card connector slot, in an attempt to contact one of the signal contacts and apply a voltage to it while a card lies fully inserted in the slot (the connector senses when a card has been fully inserted and will not operate until then). It would be useful if the signal tails lying at the rear of the connector were protected from engagement with a conductor inserted by an unauthorized person, especially from a voltage (above or below ground potential) that such conductor carried, while leaving a region above the signal tails open during soldering operations.